Selective cylinder deactivation, in which one or more cylinders of an engine are deactivated, may reduce fuel consumption during certain operating conditions, such as low engine loads. To maintain stoichiometric operation necessary for optimum operation of the three way catalyst during cylinder deactivation (e.g., to prevent flow of uncombusted intake air to the catalyst via a deactivated cylinder), engines configured to operate with cylinder deactivation may have variable valve lift systems to allow the intake valves and exhaust valves of deactivated cylinders to remain closed while the intake valves and exhaust valves of activated cylinders continue to open and close. However, such deactivatable drive systems may be costly and increase the packaging space of the engine.
DE 10 2011 118 470 A1 has disclosed a multi-cylinder Otto-cycle engine, in which individual cylinders can be deactivated during operation. By contrast to conventional cylinder deactivation, in the case of which all of the valves of each deactivated cylinder are deactivated in order to avoid gas exchange losses, it is the case here that only the inlet valves can be deactivated, and the throttle flap for closing the inlet duct is closed and opened with a time offset in relation to a valve deactivation or reactivation in order to ensure that a transition between operation without cylinder deactivation and with cylinder deactivation is less perceptible to the driver.
The inventors herein have recognized a few issues with the above approach. In the case of said engine of the reference, considerable gas exchange losses arise during cylinder deactivation operation. Further, cumbersome deactivatable valve drives are still required.
Accordingly, an engine is provided herein to at least partly address the above issues. In one example, a multi-cylinder Otto-cycle engine comprises a cylinder head which is divided into multiple sections which each delimit a combustion chamber of a cylinder of the Otto-cycle engine and which each comprise inlet and outlet ducts, inlet and outlet valves and an ignition spark generating device which is fastened in a through hole of the cylinder head section, a throttle flap being provided for at least one cylinder head section for completely closing the corresponding inlet duct in the event of a deactivation of the associated cylinder, a first gas flow duct in the at least one cylinder head section formed between the through hole and the outlet duct, and the ignition spark generating device is in the form of a rotary slide valve with integrated ignition spark electrodes, said rotary slide valve being configured to selectively either keep the first gas flow duct closed or connect said first gas flow duct to the associated combustion chamber.
In this way, cylinder deactivation may be performed entirely without valve deactivation with decreased gas exchange losses, reduced use of structural space, and reduced cost. The region around the ignition plug provides short gas flow ducts for a gas exchange reduced losses, and the ignition plug also performs the function of a gas exchange valve. In this way, the space for the inlet and outlet valves and possibly an injection nozzle is minimally affected, and it is possible to retain existing cylinder head designs with only minor modifications.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.